Rationale:

The LWG believes the normative encouragement is already sufficiently clear, and that there are no important consequences even if it is misunderstood.

Proposed resolution:

In 20.1.5, paragraph 5, change "Implementors" to "Implementors of the library described in this International Standard".

In 20.1.5, paragraph 5, the standard says that "Implementors are encouraged to supply libraries that can accept allocators that encapsulate more general memory models and that support non-equal instances." This is intended as normative encouragement to standard library implementors. However, it is possible to interpret this sentence as applying to nonstandard third-party libraries.